Singapore sits close to the equator which means the temperature stays about the same year-round. On average, it’s hot and humid with highs around 30-31℃ and lows of about 24℃. Although rain showers can occur at any time, they are usually brief and a welcome respite from the heat.
November through February is typically monsoon season but even then, rain showers tend to be short and intense, clearing to clouds and sunshine.
All of this means that any time of year is a good time for Singapore!